Scalable Two-Mode 3-Port and 4-Port Mode Insensitive Silicon Photonic Switches

Alok Das,Guowu Zhang,Hassan Rahbardar Mojaver,Odile Liboiron-Ladouceur

doi:10.1109/lpt.2021.3076096

Abstract

We propose and experimentally demonstrate a novel design approach for scalable 3-port and 4-port mode insensitive multimode switching matrices for the first two quasi-transverse electric (TE) modes. The mode insensitive phase shifter ensures less power consumption for simultaneous multimode signal transmission in a mode division multiplexing (MDM) network. At 1550 nm, the 3-port switch exhibits approximately 2.6 dB and 3.3 dB insertion loss for the longest path with a crosstalk of at most 10 dB and 8 dB over a bandwidth of 40 nm (1530 nm to 1570 nm) for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {TE}}_{\mathrm {0}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {TE}}_{\mathrm {1}}$ </tex-math></inline-formula> modes, respectively. The insertion loss measured for the 4-port switch is approximately 2.7 dB and 3.6 dB at 1550 nm with a corresponding crosstalk less than 8 dB for the two TE modes, respectively. The payload transmission is also performed using both 10 Gb/s non-return-to-zero (NRZ) and 14.0625 Gbaud 4-level pulse-amplitude modulation (PAM4) pseudorandom binary sequence (PRBS)-31 data signal to analyze the performance of the switches. Clear open eyes are observed for both single-mode and simultaneous two-mode transmissions. The low insertion loss, low intermodal crosstalk over a large optical bandwidth, and the clear open eye validate the scalability of the proposed switches for larger port count and higher-order modes.

Highlights

T HE advancement of silicon photonics (SiPh) technology in communication systems has been rising rapidly for over a decade
This letter experimentally demonstrates a novel design of mode insensitive 3-port and 4-port switches for the first two quasi-transverse electric (TE) modes that provide low insertion loss, intermodal crosstalk, and power consumption with a dynamic control by mode insensitive phase shifter
Mode insensitive switch for higher-order modes is still challenging to realize due to large insertion loss and intermodal crosstalk induced by the complex building blocks such as multimode S-bend, waveguide crossing, and mode insensitive phase shifter

Summary

INTRODUCTION

T HE advancement of silicon photonics (SiPh) technology in communication systems has been rising rapidly for over a decade. SiPh interconnects can provide large capacity, low latency, low power consumption, and high-speed data communication density within a small footprint in data center networks. Various SiPh devices have been developed to extend the capacity for MDM networks, such as mode multiplexer/de-multiplexer [3], switchable mode exchanger [4], multimode optical switches [5]–[12], power splitter [13], and more. Single-mode optical switches are used to switch the signals for different outputs This process is stable, but a large footprint and high power consumption are the bottlenecks of it. This letter experimentally demonstrates a novel design of mode insensitive 3-port and 4-port switches for the first two quasi-transverse electric (TE) modes that provide low insertion loss, intermodal crosstalk, and power consumption with a dynamic control by mode insensitive phase shifter.

BUILDING BLOCKS AND DESIGN TOPOLOGY

EXPERIMENTAL RESULTS

CONCLUSION